1. Field of the Invention
This invention relates to an optical fiber guided projectile system particularly a tube-launched projectile system.
2. Description of the Related Art
This application is directed to an improvement of my inventions described in U.S. Pat. Nos. 4,770,374 and 4,796,833, which are specifically incorporated by reference for the purpose of providing a description of related art and background information on the function and operation of the projectile system improved by the invention of the application.
The basic elements of the projectile system provide for a groove placed in the projectile airframe. An optical fiber is placed in the groove. The projectile is fired in a conventional manner. During launch, the fiber is pulled from the groove and then deployed from a fiber holding bobbin at the rear of the projectile.
The projectile is dropped into a mortar by the soldier in a random axially-rotated orientation. At the prelaunch condition, the fiber exits the tube parallel or with a slight bow relative to the wall of the tube. The projectile is initially some 18 or so inches behind the tube exit. After ignition of the propellant charge, the projectile begins to move out of the mortar tube. As the projectile moves, the fiber not being a rigid body, remains basically in its original position external to the mortar. Inside the tube, however, the fiber buckles and collapses around the projectile. As the projectile exits the tube, the projectile has, in general, passed through the loop formed by the fiber. The fiber is wrapped around the projectile. At this point it makes little difference whether the fiber is wrapped around the projectile in a clockwise or counterclockwise direction.
As the projectile exits the mortar tube, the fiber is pulled out of the groove. Damage may be caused to the fiber if pulled out of the groove so that it bends around the end of the projectile, or if the launch process too abruptly begins to remove fiber from the bobbin. The damage is typically caused by a too abrupt change in fiber direction or other cause of a sharp bend in the fiber. Additionally, the projectile system exhibits the problem of hot launch gas blow-by while the projectile is in the mortar tube.
The objects and advantages of the invention in part will be apparent from the description which follows.